Pass-through USB controller on same IOMMU group as flash drive?

[Dacobi]

I just installed unRAID for the first time and have a Win10 VM with a Geforce on pass-through and I'd like to add keyboard and mouse via an USB switch.

 

It works if the keyboard/mouse is online when I boot the VM but it doesn't hotswap.

 

I then read that you should pass-through a separate USB controller but all ports on my motherboard show up in the same IOMMU group as the one where the unRAID flash drive is,

but it is a different bus and PCI id.

 

Is this still possible to do?

 

Is there another way to do USB hotswap?

[david279]

Get a USB PCIe card and pass that thru to your VM.

Sent from my SM-G955U using Tapatalk

[SSD]

27 minutes ago, Dacobi said:

I just installed unRAID for the first time and have a Win10 VM with a Geforce on pass-through and I'd like to add keyboard and mouse via an USB switch.

 

It works if the keyboard/mouse is online when I boot the VM but it doesn't hotswap.

 

I then read that you should pass-through a separate USB controller but all ports on my motherboard show up in the same IOMMU group as the one where the unRAID flash drive is,

but it is a different bus and PCI id.

 

Is this still possible to do?

 

Is there another way to do USB hotswap?

 

You need to make sure that your unRAID USB controller is in a separate IOMMU port from the passed through one.

 

Using a second PCIe card is an option, but not one I recommend if it can be avoided. Why? 1 - why spend the $50 or whatever if you don't need it, and 2 - you will be tying up a PCIe slot. Between HBAs, RAID controller, PCIe card for full bandwidth access to an NVMe, and multiple video cards, I find there is nothing more precious than my PCIe slots. Avoiding tying one up for such a pedestrian purpose seems a waste.

 

Following the video below should help you figure out if there is an onboard controller that can be passed through. You may need to use a USB header on the MB, which requires an inexpensive cable to expose.

 

As you noticed, BIOSes often like to combine multiple controllers onto the same IOMMU group. But I have been successful on two different motherboards. The first one took a lot of experimentation. I must have tried changing 10+ BIOS settings and combinations of settings before finding that if I disabled USB3 function, that the ports got broken apart and I could pass through easily.

 

With my current MB, which combined all the USB2 and USB3 ports in the same IOMMU group, there was no explicit feature to disable USB3 (although I tried valiantly). But I found the MB included a USB 3.1 controller that was separated out nicely. I wasn't sure it would work, but I was able to pass it through and plug my keyboard/mouse dongle (Logitech unifying receiver) and that works well. I use it on a KVM switch, and it properly disconnects and reconnects. The second USB 3.1 port on the controller is USB-C, but I think I could get an adapter and also use that for attaching a USB thumbdrive (or other accessory) to the VM.

 

 

 

 

[Dacobi]

Unfortunately I can't find an option to disable USB3.0 and I don't have an USB3.1 port.

 

I've tried all USB options I have in the BIOS, with no luck...

 

But there is one USB connector on the motherboard I haven't tried yet, I'm waiting for a cable in the mail.

[SSD]

9 hours ago, Dacobi said:

Unfortunately I can't find an option to disable USB3.0 and I don't have an USB3.1 port.

 

I've tried all USB options I have in the BIOS, with no luck...

 

But there is one USB connector on the motherboard I haven't tried yet, I'm waiting for a cable in the mail.

 

You might reach out to the motherboard vendor technical support.

 

Even if they don't know what you're talking about, you can educate them a little. And the more calls about this they get, the better chance that the company will "get it" and issue a BIOS update that fixes it. And may even make it a requirement in BIOSes for future MBs. So consider it a worthwhile investment of your time and effort, even if you don't get a solution.

 

I've had 3 motherboards that I have figured a way to pass through. Not saying it is possible with yours, but think outside the box and you might find a setting that affects how the USB controllers are assigned to IOMMU groups. USB options have the highest probability.

 

Good luck!

[Dacobi]

I've tried installing the Libvirt Hotplug USB Plugin and enabling ACS Override, but no luck.

 

Nothing shows up under  Libvirt Hotplug USB Plugin. Is it still supported? or am I missing something?

[Squid]

I've tried installing the Libvirt Hotplug USB Plugin and enabling ACS Override, but no luck.
 
Nothing shows up under  Libvirt Hotplug USB Plugin. Is it still supported? or am I missing something?

The version from dlandon is and works awesome.

Sent via Tapatalk because I'm either at work or enjoying the summer

[SSD]

13 hours ago, Squid said:

The version from dlandon is and works awesome.

 

 

Interesting. I didn't know this existed. Posted link below.

 

When I did not pass through, I experienced a random drop (after more than 2 hours of use and in the middle of typing). I also experienced minor jerkiness in mouse movement (arguably I am pretty sensitive). In addition, I remember trying to move the mouse a tiny amount, there would be no movement. And then I'd give it a little more and it'd jump over where I was trying to land. Can be very annoying esp. in something like Visio. Passthrough solved all these issues with exact same keyboard and mouse.

 

Curious if this plugin helps with my issues? I expect it would have recovered from the random drop. But other two (jerkiness and loss of precision) I expect would still occur. (I have heard few complaints like mine - so this might also have been something unique to my MB server where I tried it). Obviously this non-hotswap is a big deal for people wanting to shuffle USB memory sticks, but it is also a big deal for people that use KVM (or just KM) switches. If the USB doesn't support the hot swap capability, the KVM won't ever be able to reestablish contact with the keyboard and mouse after it is switched to a different source.

 

I think I'll try this out for a second USB to use with thumbdrives. And can try my dongle on it to see if it is smoother than my prior experience.

 

Thanks!!

 

 

 

[Dacobi]

I got PCI Pass-through to work by disabling EHCI Hand-Off and xHCI.

 

Don't know if both are necessary.